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How far away is safe?

Organics recyclers are still waiting to see if the Environment Agency (EA) will set new rules recommending that no new composting sites be situated within 250m of homes and workplaces. An EA spokeswoman told MRW that its review of environmental permitting was still “in progress” and is expected to be released by mid-June.

This move towards creating a minimum distance between composting sites and nearby homes and workplaces - referred to as ‘sensitive receptors’ - is designed to mitigate any potential health impact. The concern is around bioaerosol emissions, which are released during the composting process. Bioaerosols are airborne particles that contain living organisms, such as fungi and bacteria, and there is thought to be a link between exposure to bioaerosols and respiratory health problems.

Association for Organics Recycling managing director Jeremy Jacobs has been involved in meetings with the EA around its review. “What the EA is effectively saying is that there is going to be presumption with granting permits for facilities which have a ‘sensitive receptor’ within 250m,” he says.

He adds that the EA is also discussing the quality of site-specific risk assessments that composters located within 250m of homes or workplaces must currently provide. These must show that sites can and will maintain bioaerosols at an appropriate level. “The EA’s concern is that the quality of those site-specific risk assessments in the past has not been good,” says Jacobs. He explains that while there is a methodology in place for this type of assessment, the agency is concerned that it is not sufficiently robust.

“Because it is an organic dust people don’t think of it as being harmful, but actually it is much, much more harmful than ordinary soil dust and mineral dust” - Dr Alison Searl

The EA has a position statement on composting and potential health effects from bioaerosols because “research showed a potential risk to people’s health from bioaerosols”. According to its website, after additional research it has found “there is not enough information available to determine the risk to human health from bioaerosols from composting sites”.

IOM Consulting director of analytical services Dr Alison Searl led a study for the Department for Environment, Food and Rural Affairs published in December. She says: “There is little evidence that there are real problems [with bioaerosols] for local communities, but where there are odour issues I think something has to be addressed. That doesn’t necessarily mean enclosing your process - it means managing your process properly.”

Her concern is the long-term exposure to operatives in composting operations and other waste handling sites, warning: “I think it is really important that the industry is aware of the potential risks to worker health because although there are short-term costs in having to do more to look after your workers, it offsets a potentially massive long-term cost if people start putting in compensation claims in 20 years’ time.”

She adds that preventive steps, such as masks and filtered cabs, can be simple to implement, and says that long-term data can be seen from comparable industries such as farming and cotton production. “Because it is an organic dust people don’t think of it as being harmful, but actually it is much, much more harmful than ordinary soil dust and mineral dust.”

A study by the Health and Safety Executive published in April, Bioaerosol Emissions from Waste Composting and the Potential for Workers’ Exposure, reports that the level of bioaerosols generally decreases with distance from source, and there is “little evidence that the composting operations studied made a major contribution to the overall bioaerosol burden by a distance of 250m from activities.” But echoing Searl, it warns that workers involved in compost-handling activities could be exposed to high levels of bioaerosols if not protected, and highlights the need for continued research into the effects of long-term exposure.

Jacobs says that any new policy decisions affecting compost sites need to be based on evidence. “A decision has to be based on sound science. If they go ahead and say ‘we’re not going to permit sites within 250m’ or there is going to be a presumption against it, then by default they are almost saying that they think there is a risk. If that is the case, and the site is already in operation and has the 250m site boundaries where there are sensitive receptors, does that mean the EA is going to close them? What does that mean it is going to do to them?”

Eco Sustainable Solutions managing director Trelawney Dampney says any such new rules would have serious implications for the composting sector. “What I think it will do is push more composters down the anaerobic digestion route because it is more cost-effective than in-vessel composting,” he says. “It will provide that extra driver and send more sites under cover, although if you use a dry AD system, which leaves you with a compost, you would still be subject to the same issues.”

“The aeration requirements of totally enclosed plants are such that they can triple the energy consumption of a plant if comprehensive mitigation is to be achieved” - Harry Waters

Dampney says a move towards enclosing composting facilities would mean that operatives are exposed to higher levels of bioaerosols. But he adds that this situation would mean composting companies can better control their workers’ exposure by providing appropriate equipment.

But Agrivert commercial director Harry Waters says enclosure of sites does not make sense: “As highlighted in the HSE report, bioaerosol levels can be significantly elevated inside buildings, putting operators at risk. And the aeration requirements of totally enclosed plants are such that they can triple the energy consumption of a plant if comprehensive mitigation is to be achieved.”

Waters adds that staff health is “of paramount importance” to the company: “Although Agrivert has not experienced operators having health issues as a result of working on composting sites, we will be issuing staff with personal bioaerosol monitors to better understand exposure levels going forward.”

Jacobs, Dampney and Waters all describe new guidelines as precautionary. Waters warns: “Studies conducted on bioaerosols are limited and therefore the new guidelines have to be seen as precautionary and should be positioned so as not to alarm the general public. Composting conducted responsibly is an inherently safe process, and over-reaction to the report could jeopardise the affordability of some green waste operations that are currently delivering a significant environmental benefit.”


On 6 April 2010, Lord Redesdale asked some parliamentary questions regarding bioaerosols and composting facilities and received the following responses.

Lord Redesdale asked: “To ask Her Majesty’s Government why the Environment Agency (EA) concluded that the minimum safe distance from biological treatment facilities of residential properties or workplaces was 250m.”

Parliamentary Under-Secretary of State, Department for Environment, Food and Rural Affairs Lord Davies of Oldham replied: “The EA believes that the 250m limit is sufficiently precautionary, based on currently available knowledge. It will continue to keep under review its policy on composting and health effects and amend it, if necessary, in the light of any relevant new research or evidence.”

Lord Redesdale: “Who would meet the cost of relocating any previously identified open windrow compost site that is within 250m of a receptor and which does not have an environmental permit.”

Lord Davies: “It is for the operator to decide the best course of action for their business and to meet the cost of fulfilling the regulatory requirements.”

Lord Redesdale: “How many small-scale compost sites on farms have not met the requirements for a standard permit, in light of the EA policy statement regarding the 250m rule.”

Lord Davies: “Small-scale compost sites on farms are currently likely to operate under a registered exemption from an environmental permit. When registering such sites, the EA is not required to ask for any information beyond its regulatory remit and therefore does not hold information on whether an exempt site is a farm or not.”

Lord Redesdale: “Has the EA considered the environmental impact of moving compost sites further away from the waste arisings in considering the 250m rule.”

Lord Davies: “The EA has not made any changes to regulation that would require existing permitted composting sites to relocate. The agency has not considered the environmental impact of moving composting sites. Any operators that want to relocate their operations would need to consider the environmental impacts.”

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